Ontogenetic development and community structure
Analyses of the dynamics of consumer-resource and cannibalistic systems show
how different body-size scalings impact population dynamics and temporal
changes in body-size distributions. Size-structured dynamics in these systems
also have the potential to result in alternative states, which, particularly in
cannibalistic systems, may result in very different size distributions (Claessen &
De Roos,2003). An extension of physiologically structured population models to
more complex trophic configurations will further increase the likelihood of
alternative states. In the following, we discuss alternative states and body-size
distributions of populations exemplified by tritrophic food chains and tritro-
phic configurations with life-history omnivory.
Since the classical paper by Brooks and Dodson ( 1965 ) it is generally accepted
that size-dependent predation by top predators has a strong structuring impact
on prey size distributions. Size-dependent predation in combination with food-
dependent development in prey has the potential to lead to alternative stable
states with vastly different size distributions of the prey (De Roos & Persson,
2002 ). In the tritrophic food chain studied by De Roos and Persson (2002), two400
10001993(^8001995)
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(a) (b)
Figure 12.4(a) Examples of growth curves (mean1 SD) of perch becoming stunted (born
in 1986) and becoming giants (born in 1990) in Lake Abborrtja ̈rn 3. (b) Shift in perch size
distributions between stunted (1993) and giant phases (1995). The main part of the size
distribution in 1993 consisted of stunted mature perch with a median size of 156mm. The
main part of the size distribution in 1995 consisted of small immature perch on which a
few large mature perch are feeding (data from Perssonet al., 2003).
INDIVIDUAL GROWTH AND BODY SIZE 235